public class Solution2 {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param head ListNode类
     * @return ListNode类
     */
    public ListNode deleteDuplicates (ListNode head) {
        // write code here
        ListNode cur = head;
        while (cur != null && cur.next != null) {
            if (cur.val == cur.next.val) {
                if(cur.next.next == null) {
                    cur.next = null;
                } else {
                    cur.next = cur.next.next;
                }
            } else {
                cur = cur.next;
            }
        }
        return head;    }
}
